* Add new contextualized API for hooks and steps
* Make default context configurable
* Run AfterStep hooks even after failed steps, fixes#370
* Update CHANGELOG and README
* Add step result status to After hook, fixes#378
* Elaborate hooks documentation
* Add test to pass state between contextualized steps
* Update README with example of passing state between steps
Issue: It is not possible to use function without return when
matching steps, resulting in a lot of Nil only error
returns.
Fix: Allows to provide empty result function by correctly matching
reflect Calls on step Handler.
When nothing is returned by the Handler, it will return
nil as if errors was nil.
